泥岩裂缝性储层应力敏感性实验研究

Experimental Study on Pressure-sensibility of Fractured Shale Reservoir

为准确评价泥岩裂缝性储层在不同压力条件下的应力敏感性,在理论研究基础上,对基质渗透率非常低的天然泥岩进行人工造缝。模拟地下泥岩裂缝状态,采用氮气作为流动介质通过高温覆压孔渗测定仪实验测量不同外压条件下造缝后泥岩岩心渗透率变化规律。实验结果表明:泥岩裂缝的渗透率随外压和内压增大呈非线性函数关系变化。外压敏感指数远大于内压敏感指数。不论是外压还是内压作用,都呈现出加载过程中的敏感指数大于卸载过程中的敏感指数。

Fracture reservoir in Daqing Oilfield during the exploitation of oil and gas fields,mudstone fracture have problems with closure.And the conventional sandstone reservoir oil production mechanism is not same.With exploitation of an oilfield extending fracture stress sensitivity has great effect on declining production decline and lessening the oil output in mudstone fractured reservoir.So during production practice a strict control should be exercised over production pressure difference.If production pressure difference becomes too big,rock micro-cracks are nearly closedand is capable to the reservoir permeability less so that productivity of producers was reduced.Nitrogen used as flow media.High temperature and overburden pressure porosity permeability experimental instrument is used in the test to mudstone crack sensitivity are carried out with various confining pressure and pore pressure.The experimental results show that with the increase of pressure and pore pressure the permeability of mudstone cracks change nonlinearly with pressure and pore pressure.Pressure sensitive index is greater than pore pressure index.Both the processes of pressure and the processes of pore pressure demonstrate that sensitive index in the preceding process of increase pressure is greater than sensitive index in the preceding process of reduce pressure.